Pagoda Rock

[Shireen Gonzaga <whimbrel at comcast_net>]

I once asked what Pagoda rock was made of, and I
think others on this list have wondered too.

Here's the answer: chert

from http://geology.about.com/library/bl/images/blchert.htm
(image of 2 nice specimens in that page)
   Striped chert pebbles like these are common along
   parts of the California coast. Chert is a rock type
   composed mostly of the mineral chalcedony-
   cryptocrystalline silica, that is, quartz in crystals of
   submicroscopic size. It can form in parts of the deep
   sea where the tiny shells of siliceous organisms are
   concentrated, or where underground fluids replace
   sediments with silica. Chert nodules also occur in
   altered limestones.

There's more info at that webpage.

Some of the pagoda rock I've seen at a LFS has a
rusty color to it and is quite heavy. The above-
mentioned website says that reddish chert is associated
with iron deposits, and is called jasper. This is a
*very* attractive rock.

For some stunning examples of pagoda rock as
used in suiseki, see
http://www.skeetmcauley.net/suiseki/suiseki.html

- sg

--
Shireen Gonzaga
Baltimore
whimbrel at comcast_net